This paper considers the phenomenon of horizontal cooperation between state party organizations. The assumption of cooperation among political party organizations comes from the fact that they share voters. National political party organizations are trying to reach the same voters as state and local party organizations and these groups often coordinate their efforts to share resources and to maximize efficiency and effectiveness in their joint missions. There is less of an obvious explanation for why party organizations covering non-overlapping jurisdictions would coordinate their efforts, especially by sharing potentially scarce resources. This research considers cooperation between state central committees (both Democratic and Republican) through the transfer of money during each election cycle from 2000 to 2008. Preliminary analyses indicate that these contributions are largely driven by self interested exchanges of differently regulated campaign funds. Other explanations to be tested are that state parties are more likely to engage in these exchanges with geographic neighbors, with ideologically similar parties, and when the leadership of the parties engages more extensively with larger national party network.